Direct measurement of HDL cholesterol: Method eliminating apolipoprotein E‐rich particles

It has been reported that the existing direct method of high density lipoprotein (HDL) cholesterol measures particles enriched with apolipoprotein E (apoE). The aim of our study was to investigate a new analytical protocol to directly measure HDL cholesterol that eliminates apoE‐rich particles. The interactions of four lipoproteins (HDL 3 , HDL 2 , LDL, and VLDL + chylomicron) with surfactants, divalent cations, sugars, and lectins were investigated. By analyzing sera, HDL 3 , and HDL 2 , we examined the relationships among the measurements obtained by our protocol, a precipitation method using heparin‐MnCl 2 , and a commercially available kit for this direct method. A significant difference was found between the direct method and the heparin‐MnCl 2 method, but not between our protocol and the heparin‐MnCl 2 method. Multiple regression analysis showed that the difference between the direct method and the heparin MnCl 2 method is dependent on sources of apoE‐rich HDL. In conclusion, our protocol enables a direct measurement of HDL cholesterol that eliminates apoE‐rich particles. J. Clin. Lab. Anal. 15:223–229, 2001. © 2001 Wiley‐Liss, Inc.